1. Field of the Invention
The present invention relates to systems and methods for providing satellite broadcast services, and in particular to a low cost system for increasing channel capacity in a satellite broadcast network.
2. Description of the Related Art
The past decade has seen the development of Direct Broadcast Satellite (DBS) services for providing video, audio, data, and other program material to subscribers. The electromagnetic spectrum allocated for DBS in the United States has been limited to 500 MHz. This constraint limits the maximum number of channels that existing DBS service can offer from one geostationary orbit (GSO) slot, since each video channel typically occupies about 2-6 MHz of bandwidth, depending on the data rates. This shortage of spectrum/channels becomes worse with the emerging demand for High Definition TV (HDTV) which requires much higher bandwidth per channel than traditional video channels. The shortage of spectrum and channels is made even more apparent with the recent approval for DBS operators to provide local programming. Three are an estimated 200 or more local TV stations spreading over the domestic markets, and DBS operators will not be able to cover all cities through their existing fleet of satellites, if the demand on extending channel numbers continue to grow.
One possible solution is to use another GSO orbital slot for DBS services. However, using another GSO slot is not a permanent solution, because the 9 degree orbit slot spacing requirement for satellites broadcasting at DBS frequencies allow only few slots for giving service regions (e.g. the continental United States, or CONUS) and these orbital slots are almost all taken.
Another possible solution is to use different or additional frequency bands to transmit the additional information. Unfortunately, this solution requires that each subscriber's receiver include additional circuitry to detect and demodulate the information on the additional frequency bands. Further, this solution faces the formidable task of overcoming the regulatory process to acquire the required spectrum.
What is needed is a system and method for providing high bandwidth DBS services that augment current DBS systems in a non-interfering way. The present invention satisfies that need.